Marty says

the logo refers to a letter case which contains different types of letters. there we have an arabic, chinese, hebrew and a latin letter and various symbols. the letter in the middle means beauty. the logo for a white background has an outline on the top left in order to be able to see the borders of the letter case.

it refers as well to the square of the OCAL logo and (*tataaa*) continues the color spectrum (yes, I really like this idea ;))